This invention generally relates to the field of the preparation of slides for microscopic review. Cytology is a branch of biology dealing with the study of the formation, structure, morphology, and function of cells. As applied in a laboratory setting, cytologists, cytotechnologists, and other medical professionals make medical diagnoses of a patient's condition based on visual examination of a specimen of the patient's cells. A typical cytological technique is a “pap smear” test, in which cells are scraped from a woman's cervix and analyzed microscopically in order to detect the presence of abnormal cells, a precursor to the onset of cervical cancer. Cytological techniques are also used to detect abnormal cells and disease in other parts of the human body.
Cytological techniques are widely employed because collection of cell samples for analysis is generally less invasive than traditional surgical pathological procedures such as biopsies, whereby a tissue specimen is excised from the patient using specialized biopsy needles having spring loaded translatable stylets, fixed cannulae, and the like. Cell samples may be obtained from the patient by a variety of techniques including, for example, by scraping or swabbing an area, or by using a needle to aspirate body fluids from the chest cavity, bladder, spinal canal, or other appropriate area. In the processing of tissues for glass slides, the tissues are clinically removed from a patient and placed in a container that often contains a preservative and/or fixative and is then transported to the lab for further treatment or conditioning.
It is generally desirable that the cells on a slide have a proper spatial distribution, so that individual cells can be examined. A single layer of cells is typically preferred. Accordingly, preparing a specimen from a fluid sample containing many cells typically requires that the cells first be separated from each other by mechanical dispersion, fluidic shear, or other techniques so that a thin, monolayer of cells can be collected and deposited on the slide. In this manner, the cytotechnologists can more readily discern abnormal cells. The cells are also able to be counted to ensure that an adequate number of cells have been evaluated. Certain methods and apparatus for generating a thin monolayer of cells on a slide advantageous for visual examination are disclosed in U.S. Pat. No. 5,143,627 issued to Lapidus et al. and entitled “Method and Apparatus for Preparing Cells for Examination;” U.S. Pat. No. 5,240,606 issued to Lapidus et al. and entitled “Apparatus for Preparing Cells for Examination;” U.S. Pat. No. 5,269,918 issued to Lapidus et al. and entitled “Clinical Cartridge Apparatus;” and U.S. Pat. No. 5,282,978 issued to Polk, Jr. et al. and entitled “Specimen Processor Method and Apparatus,” all of which are assigned to the assignee of the present invention and all of the disclosures of which are incorporated herein by reference in their entirety.
Once a specimen slide is prepared, the cells can be fixed by either submersing the slide in an alcohol bath or spraying the cells with an alcohol solution. Once fixed, the specimen slide may be stained by manual, semi automated, or automated systems (for example, Dako Autostainer (DakoCytomation Ltd., Ely, United Kingdom). Stained slides are then coverslipped by the application of mounting media which affixes the coverslip to the slide base by the adhesive action of the mounting media.
After being fixed and stained, the specimen may be visually inspected by a cytotechnologists, typically under magnification, and with or without various sources of illumination. Alternatively or additionally, automated machine vision systems have been adapted to aid cytological inspection. For example, an automated vision system may perform a preliminary assessment of the entire slide on which the specimen is disposed to alert the cytotechnologists to potentially the most relevant areas of the slide for close inspection, or may be used to rescreen specimens already analyzed by the cytotechnologists.
Automated specimen processing machines (e.g., ThinPrep® 3000 Processor; Cytyc Corporation, Marlborough, Mass.) prepare microscope slides by transferring cell samples to glass slides. Once the cell samples have been transferred to the slide, the cell sample is fixed through the application of an alcohol solution to the cells. The fixation solution usually contains about 50% ethanol and polyethylene glycol and is applied to the slides in a fine mist. The fixation solution fixes the cells and subsequently evaporates in a short period of time. Although the application of the alcohol based fixation solution in such a manner allows for rapid processing of cell samples, the resultant fine mist of the fixation solution may be spread over a wide area and may result in the accumulation of the fixation solution on other parts of the automated slide processor. Build up of residue of fixation solution is a potential source of instrument error and thus regular maintenance is necessary to keep the slide processor running properly.
Thus, the present invention relates to a cell fixation solution that contains a radiation activated curing polymer that allows a cell sample to be simultaneously fixed and coverslipped.